November 1999 PRELIMINARY FEATURING P POWER SO ance High-Perform age ipation Pack Thermal Diss ML6554 3A Bus Termination Regulator GENERAL DESCRIPTION FEATURES The ML6554 switching regulator is designed to convert voltage supplies ranging from 2.3V to 4V into a desired output voltage or termination voltage for various applications. The ML6554 can be implemented to produce regulated output voltages in two different modes. In the default mode, when the VREF pin is open, the ML6554 output voltage is 50% of the voltage applied to VCCQ. The ML6554 can also be used to produce various user-defined voltages by forcing a voltage on the VREFIN pin. In this case, the output voltage follows the input VREFIN voltage. The switching regulator is capable of sourcing or sinking up to 3A of current while regulating an output VTT voltage to within 3% or less. ■ Power SOP package ■ Can source and sink up to 3A, no heat sink required ■ Integrated Power MOSFETs ■ Generates termination voltages for SSTL-2 SDRAM, SGRAM, or equivalent memories ■ Generates termination voltages for active termination schemes for GTL+, Rambus, VME, LV-TTL, PECL and other high speed logic ■ VREF input available for external voltage divider ■ Separate voltages for VCCQ and PVDD ■ Buffered VREF output ■ VOUT of ±3% or less at 3A ■ Minimum external components ■ Shutdown for standby or suspend mode operation ■ Thermal Shutdown » 130ºC The ML6554, used in conjunction with series termination resistors, provides an excellent voltage source for active termination schemes of high speed transmission lines as those seen in high speed memory buses and distributed backplane designs. The voltage output of the regulator can be used as a termination voltage for other bus interface standards such as SSTL, CMOS, Rambus™, GTL+, VME, LV-CMOS, LV-TTL, and PECL. BLOCK DIAGRAM 15 VCCQ 16 AVCC 14 1 VREFOUT 9 VDD 12 VDD SHDN 2 PVDD1 7 VL1 (VOUT) OSCILLATOR/ RAMP GENERATOR 200kΩ 3 + S – VREF BUFFER 11 PVDD2 – R + VREFIN + 200kΩ AGND – ERROR AMP Q VL2 (VOUT) Q 6 RAMP COMPARATOR 13 10 VFB 8 DGND 4 PGND1 5 PGND2 1 ML6554 PIN CONFIGURATION ML6554 16-Pin PSOP (U16) VDD 1 16 AVCC PVDD1 2 15 VCCQ VL1 3 14 VREFOUT PGND1 4 13 AGND PGND2 5 12 SHDN VL2 6 11 VREFIN PVDD2 7 10 VFB DGND 8 9 VDD TOP VIEW PIN DESCRIPTION PIN NAME FUNCTION 1 V DD 2 PIN NAME FUNCTION Digital supply voltage 9 V DD Digital supply voltage PVDD1 Voltage supply for internal power transistors 10 V FB Input for external compensation feedback 3 VL1 Output voltage/ inductor connection 11 VREFIN Input for external reference voltage 4 P GND1 Ground for output power transistors 12 SHDN Shutdown active low. CMOS input level P GND2 Ground for output power transistors 13 AGND 6 VL2 Output voltage/inductor connection Ground for internal reference voltage divider 7 PVDD2 Voltage supply for internal power transistors 14 VREFOUT Reference voltage output 15 8 D GND Digital ground VCCQ Voltage reference for internal voltage divider 16 AVCC Analog voltage supply 5 2 NOVEMBER, 1999 ML6554 ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. Lead Temperature (Soldering, 10 sec) .............................. Thermal Resistance (qJC)(Note 3) ........................... 2°C/W Output Current, Source or Sink ................................. 3.0A PV DD .......................................................................................... 5.0V Voltage on Any Other Pin ...... GND – 0.3V to VIN + 0.3V Average Switch Current (IAVG) .................................. 3.0A Junction Temperature ....................................................... Storage Temperature Range ............................................. OPERATING CONDITIONS Temperature Range ....................................... 0°C to 70°C PVDD Operating Range ................................ 2.0V to 4.0V ELECTRICAL CHARACTERISTICS Unless otherwise specified, PVDD = 3.3V±10%, TA = Operating Temperature Range (Note 1) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS SWITCHING REGULATOR V TT Output Voltage, SSTL_2 IOUT = 0, VCCQ = 2.3V 1.12 1.15 1.18 V (See Figure 1) VREF = open VCCQ = 2.5V 1.22 1.25 1.28 V Note 2 VCCQ = 2.7V 1.32 1.35 1.38 V IOUT = ±3A, VCCQ = 2.3V 1.09 1.15 1.21 V VREF = open VCCQ = 2.5V 1.19 1.25 1.31 V Note 2 VCCQ = 2.7V 1.28 1.35 1.42 V IOUT = 0 VCCQ = 2.3V 1.139 1.15 1.162 V Note 2 VCCQ = 2.5V 1.238 1.25 1.263 V VCCQ = 2.7V 1.337 1.35 1.364 V VREFOUT Internal Resistor Divider ZIN VREF Reference Pin Input Impedance Note 2 VCCQ = 0 Switching Frequency DVOFFSET Offset Voltage VTT – VREFOUT VCCA = 2.5V No Load VCCQ = 2.5 100 kW 650 kHz –12.5 12.5 mV SUPPLY IQ Quiescent Current IOUT = 0, no load IVCCQ 10 µA I AVCC 500 µA I DVCC 7 mA BUFFER IREF Output Load Current 3 mA Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions. Note 2: AVCC, PVDD = 3.3V ±10% Note 3: Infinite heat sink NOVEMBER, 1999 3 ML6554 FUNCTIONAL DESCRIPTION This switching regulator is capable of sinking and sourcing 3A of current without an external heatsink. The ML6554 uses a power surface mount package (PSOP) that includes an integrated heat slug. The heat can be piped through the bottom of the device and onto the PCB (Figure 2). Output voltage can also be selected by forcing a voltage at the VREFIN pin. In this case, the output voltage follows the voltage at the VREFIN input. Simple voltage dividers can be used this case to produce a wide variety of output voltages between 2.3V to 4V. The ML6554 integrates two power MOSFETs that can be used to source and sink 3A of current while maintaining a tight voltage regulation. Using the external feedback, the output can be regulated well within 3% or less, depending on the external components chosen. Separate voltage supply inputs have been added to accommodate applications with various power supplies for the databus and power buses. VREF INPUT AND OUTPUT OUTPUTS OTHER SUPPLY VOLTAGES The output voltage pins (VL1, VL2) are tied to the databus, address, or clock lines via an external inductor. See the Applications section for recommendations. Output voltage is determined by the VCCQ or VREFIN inputs. Several inputs are provide for the supply voltages: PVDD1, PVDD2, AVCC, and VDD. The VREFIN input can be used to force a voltage at the outputs (Inputs section, above). The VREFOUT pin is an output pin that is driven by a small output buffer to provide the VREF signal to other devices in the system. The output buffer is capable of driving several output loads. The output buffer can handle 3mA. The PVDD1 and PVDD2 and provide the power supply to the power MOSFETs. VDD provides the voltage supply to the digital sections, while AVCC supplies the voltage for the analog sections. Again, see the Applications section for recommendations. INPUTS The input voltage pins (VCCQ or VREFIN) determine the output voltages (VL1 or VL2) . In the default mode, where the VREFIN pin is floating, the output voltage is 50% of the VCCQ input. VCCQ can be the reference voltage for the databus. FEEDBACK INPUT The VFB pin is an input that can be used for closed loop compensation. This input is derived from the voltage output. See application section for recommendation. 2.5V TO 4V C8 0.1µF R2 100Ω C9 0.1µF R1 100Ω R3 100kΩ 220µF 220µF U1 ML6554 1 TPI 2 L1 3.3µH C3 0.1µF VTT C1 820µF F2V OS-CON 4 5 C2 0.1µF C4 0.1µF TO SDRAMS 3 6 7 8 VDD AVCC PVDD1 VCCQ VL1 VREFOUT PGND1 AGND PGND2 SHDN VL2 VREFIN PVDD2 VFB DGND VDD 16 15 14 VCCQ VREFOUT 13 12 11 SHDN VREFIN 10 9 R4 100kΩ R5 1kΩ C7 1nF GND GND Figure 1. 4 NOVEMBER, 1999 ML6554 APPLICATIONS USING THE ML6554 FOR SSTL BUS TERMINATION The circuit schematic in Figure 1 shows a recommended approach for an constructing a bus terminating solution for an SSTL-2 bus. This circuit can be used in PC memory and Graphics memory applications as shown in Figures 3 and 4. Note that the ML6554 can provide the voltage reference (VREF) and terminating voltages (VTT). Using the layout as shown in Figures 5, 6, and 7, and measuring the VTT performance using the test setup as described in Figure 8, the ML6554 delivered a VTT ± 20mV for 1A to 3A loads (see Figure 9). Table 1 provides a recommended parts list. For more recent Applications Notes or Evaluation Boards contact Micro Linear. Airflow is not likely to be needed in the operation of this device (assuming a board layout similar to that described above). The power handling performance of the PSOP package is shown by a study of the package manufacturer for various airflow vs. qJA conditions in Figure 10. BUS TERMINATION SOLUTIONS FOR OTHER BUSES Table 2 provides a summary of various bus termination VREF & VTT requirements. The ML6554 can be used for those applications. POWER HANDLING CAPABILITY OF THE PSOP PACKAGE Using the board layout shown in Figures 5,6, and 7; soldering the ML6554 to the board at zero LFPM the temperature around the package measured 55 ºC for 3A loads. Note that a 1ounce copper plane was used in the board construction. HEAT SLUG Figure 2. Cutaway view of PSOP Package NOVEMBER, 1999 5 ML6554 168/184/208-PIN DIMM CONNECTORS AND SDRAM/SGRAM MODULES TERMINATION RESISTORS PC CHIP SET NORTHBRIDGE DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES TERMINATION RESISTORS VTT ML6554 VREF Figure 3. Complete Termination Solution PC Main Memory (PC Motherboard) 6 NOVEMBER, 1999 ML6554 SO DIMM AND MODULES 3D GRAPHIC CHIP TERMINATION RESISTORS SGRAM DATA LINE, CLOCK LINES, ADDRESS LINES, CONTROL LINES TERMINATION RESISTORS VREF ML6554 2.5V VOLTAGE REGULATOR VTT 5V OR 3.3V AGP/PCI BUS Figure 4. Complete Termination Solution Graphics Memory Bus – AGP Graphics Cards NOVEMBER, 1999 7 ML6554 Figure 5. Top Silk Figure 6. Top Layer 8 Figure 7. Bottom Layer NOVEMBER, 1999 ML6554 3.3V POWER SUPPLY V A ACTIVE CLAMP VDD VCCQ VCCQ SUPPLY ML6554 EVAL VTT CURRENT SOURCE/SINK POWER SUPPLY GND A Figure 8. Test Circuit Setup VTT VARIANCE WITH VDD@ITT (VCCQ 2.5V) TESTED WITH EVAL PCB ITT 1.29 3A SINKING 2A SINKING 1.28 1A SINKING VTT (V) V ITT 0A SINKING 1.27 3A SOURCING 2A SOURCING 1.26 2.0 2.5 3.0 3.5 4.0 1A SOURCING VDD (V) Figure 9. VTT Performance for SSTL-2 Bus NOVEMBER, 1999 9 ML6554 ITEM QTY DESCRIPTION MANUFACTURER / PART NUMBER DESIGNATOR RESISTORS 1 2 3 CAPACITORS 2 1 2 100W1210 SMD 1kW 1210 SMD 100kW1210 SMD Panasonic/ERJ-8ENF1000V Panasonic/ERJ-8ENF1001V Panasonic/ERJ-8ENF1003V R1, R2 R5 R3, R4 4 3 0.1µF 1210 Film SMD C2, C8, C9 5 6 7 8 ICS 1 2 1 2 820µF 2V Solid Elect. SMD 330µF Tant 6.3V 100mW 1nF 1210 Film SMD 0.1µF 0805 Film Panasonic/ECV3VB1E104K Panasonic/ECU-V1H104KBW Sanyo/ 2SV820M Os Con AVX/ TPSE337M006R0100 Panasonic/ECU-V1H102KBM Panasonic/ECJ-2VF1C104Z C1 C5, C6 C7 C3, C4 9 1 ML6554 Bus Terminator Power SOP Package ML6554CU U1 1 3.3µH 5A inductor SMD Coilcraft/D03316P-332HC Pulse Eng./ P0751.332T Gowanda/SMP3316-331M XFMRS inc./XF0046-S4 L1 1 1 Scope probe socket 12 Pin breakaway strip Tektronics/131-4353-00 Sullins/PTC36SAAN (36 PINS) TP1 I/O, standoffs MAGNETICS 10 OTHER 11 12 Table 1. Recommend Parts List for SSTL-2 Termination Circuit VENDOR LIST 1. AVX (207) 282-5111 2. Sanyo (619) 661-6835 3. Tektronix (408) 496-0800 4. Coilcraft (847) 639-6400 5. Pulse (800) 797-8573 6. Gowanda (716) 532-2234 7. Xfmrs Inc. (317) 834-1066 8. Panasonic (714) 373-7366 9. Digikey (800) 344-4539 10 NOVEMBER, 1999 ML6554 60 40 40 θJA (ºC/W) ΘJA (ºC/W) 60 20 20 16Ld PSOP2 2.3x3.1mm PAD 1.9mm DIE 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 16Ld PSOP2 2.3x3.1mm PAD 1.9mm DIE @ 0.8 WATTS 0 0 200 100 300 400 POWER (W) AIR VELOCITY (LFPM) NATURAL CONVECTION ΘJA TEST RESULTS 1.27mm PITCH PowerSOP™ 2 SLUG SOLDERED FORCED CONVECTION ΘJA TEST RESULTS 1.27mm PITCH PowerSOP™ 2 SLUG SOLDERED 500 Figure 10. Graphical Results Summary – 1S2P Test Board DRAWING NUMBER ENG-CB-1007 REV A Applicable Jedec Spec JC 51-X (Note 1) (Sroposed Spec) Substrate Material FR-4 Dimensions (LxW) (Overall) 114.3 x 76.2mm Dimensions (LxW) (Metallization) 55 x 65mm Dimensions (LxW) (Inner Planes) 73 x 73mm Thickness 1.6 mm Pitch 1.27mm Stackup (# Signal Layers, # Cu Planes) 1S2P Cu Trace Coverage (Signal Layer) 12% Cu Coverage (Internal Layer) 100% Trace Width (Spec/Measured) 235.5±25.5/288µm Trace Cu Thickness (Spec/Measured) 70±14/67µm Inner Cu Thickness (Spec/Measured) 35±3.5/31µm Build # C1797 Note 1: Proposed Spec "Thermal Test Board with Two Internal Solid Copper Planes for leaded Surface Mount Packages". Figure 11. Test Board Layout for QJA vs. Airflow NOVEMBER, 1999 11 ML6554 BUS DESCRIPTION DRIVING METHOD GTL+ Gunning Transceiver Bus Plus Open Drain SSTL_2 Series Stub Terminated Logic for 2V RAMBUS LV-TTL VDDQ VTT VREF MICRO LINEAR SOUTIONS 5v or 3.3V 1.5V±10% Note 10 Note12 1.0V±2% Note 11 ML6554CU; Mode: VREF Input = 1.5V, VCC = 5V Symmetric Drive, Series Resistance 2.5V±10% 0.5x(VDDQ) ±3% 2.5V RAMBUS Signaling Logic Open Drain None Specified 2.5V 2.0V Low Voltage TTL Logic or PECL or 3.3V VME Symmetric Drive 3.3±10% VDDQ/2 3.3V ML6554CU or ML6553CS; Mode: VREF Input = Floating or Forced, VCC = 3.3V ML6553CS; Mode: VREF Input = Open, VCC = VDDQ ML6553CS; Mode: VREF Input = Open, VCC = VDDQ Table 2. Termination Solutions Summary By Buss Type 12 NOVEMBER, 1999 INDUSTRY SYSTEM COMPONENTS 300 to 500MHz Processor; PC Chipsets; GTLP 16xxx Buffers; Fairchild, Texas Instr. SSTL SDRAM; Hitachi, Fujitsu, NEC, Micro, Mitsubishi nDRAM, RAMBUS, Intel, Toshiba Processors or backplanes; LV-TTL SDRAM, EDO RAM ML6554 PHYSICAL DIMENSIONS inches (millimeters) Package: U16 16-Pin PSOP 0.386 - 0.393 9.80 - 9.98 HEAT SLUG DIMENSIONS: 0.079 × 0.279 (2.01 × 7.09) 16 PIN 1 ID HEAT SLUG 0.150 - 0.157 0.230 - 0.244 3.81 - 3.99 (5.84 - 6.20) 1 0.017 - 0.027 0.43 - 0.69 (4 PLACES) 0.050 BSC (1.27 BSC) 0.061 - 0.068 (1.55 - 1.73) 0º - 8º 0.055 - 0.061 (1.40 - 1.55) 0.014 - 0.019 (0.35 - 0.49) SEATING PLANE 0.00 - 0.004 (0.127 - 0.25) 0.016 - 0.035 (0.41 - 0.89) 0.0075 - 0.0098 (0.19 - 0.25) ORDERING INFORMATION PART NUMBER TEMPERATURE RANGE PACKAGE ML6554CU 0°C to 70°C 16-Pin PSOP (U16) Micro Linear Corporation 2092 Concourse Drive San Jose, CA 95131 Tel: (408) 433-5200 Fax: (408) 432-0295 www.microlinear.com © Micro Linear 1999. property of their respective owners. is a registered trademark of Micro Linear Corporation. All other trademarks are the Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223; 5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending. Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. No license, express or implied, by estoppel or otherwise, to any patents or other intellectual property rights is granted by this document. The circuits contained in this document are offered as possible applications only. Particular uses or applications may invalidate some of the specifications and/or product descriptions contained herein. The customer is urged to perform its own engineering review before deciding on a particular application. Micro Linear assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear products including liability or warranties relating to merchantability, fitness for a particular purpose, or infringement of any intellectual property right. Micro Linear products are not designed for use in medical, life saving, or life sustaining applications. DS6554-01 NOVEMBER, 1999 13 To receive a price quote or to request a product sample, call or send e-mail to your local representative. When sending e-mail, be sure to include the Micro Linear part number and whether you want a price quote or a sample in the subject line. (i.e. subject: Sample request - ML part#xxxx) Click here to find your local representative